This invention relates to electronic throttle control mechanisms for internal combustion engines.
Valve assemblies for engines and related systems typically utilize rotatable valve members in fluid flow passageways to assist in regulating fluid flow through them. For example, throttle valve members are positioned in air induction passageways for internal combustion engines. The valve assemblies are controlled either mechanically or electronically and utilize a mechanism which directly operates the valve member.
For consideration such as weight, cost, and ease of manufacturing, it is preferred to have the body, cover, and some of the component members or mechanisms made from plastic materials, such as plastic composite materials. However, these materials often can expand or contract in the temperature range extremes typically experienced in vehicle engine environments. Moreover, certain operational components, such as gear members and rotatable shaft members, should be accurately positioned at all times for optimum operations. Also, it is preferable for the motors for electronic throttle control systems to not be enclosed in composite housings due to the need to dissipate heat generated in the use of the systems.
It would be desirable to have an electronic valve control system with a plastic composite housing and cover member and which accurately maintains the operating components in position at all times. It also would be desirable to have an electronic valve control system with an injection molded housing which incorporates the motor in the molding process and still allows sufficient dissipation of generated heat.
It is an object of the present invention to provide an improved electronic valve control system which utilizes molded plastic composite materials and accurately maintains the position of operating components. It is a further object of the present invention to provide an improved electronic throttle control assembly in which the motor is injection molded as part of the housing.
In accordance with the present invention, a metal motor mounting plate is provided which is insert injection molded into the plastic composite material forming the housing. A gear shaft is mounted in the metal mounting plate so that it will be accurately positioned for use with the operational mechanism of the electronic throttle control system. The motor is attached to the mounting plate prior to the injection molding procedure, and the mold and injection molded materials only covers a portion of the motor. Shutoff areas in the mold prevent the injected plastic material from covering certain areas of the motor and gear shaft.
Other features and advantages of the present invention will become apparent from the following description of the invention, particularly when viewed in accordance with the accompanying drawings and appended claims.